Powder-actuated tool

ABSTRACT

A power-actuated fastening tool of the type for driving fasteners by a propellant charge wherein a fastener driving member has an enlarged head portion. The head portion is so designed that a portion of the gases generated by the propellant charge may bleed from the rearward side to the forward side thereof to reduce recoil and buffer the fastener driving member. In addition, a specially designed piston member is provided for driving threaded fasteners wherein the piston has a bore extending into its forward end with the innermost portion of the bore being defined by a conical wall. The tool is so designed that power adjustment is obtained by positioning the piston member into its driving position by insertion of a fastener into the muzzle end of the tool. The barrel guide slot and pawl member are so designed that upon opening of the tool, there will be planar contact between the two members.

United States Patent 5 Bakoledis [54] POWDER-ACTUATED TOOL [72] Inventor: Andrew G. Bakoledis, Clinton,

Conn.

[73] Assignee: Olin Corporation [22] Filed: Dec. 7, 1970 [21] Appl. No.: 95,620

[52] US. Cl ..227/l0 [51] Int. Cl ..B25c H14 [58] Field of Search ..227/8, 9, 10, 11, 130

[56] References Cited UNITED STATES PATENTS 3,101,476 8/1963 Wandel .;.....227/13o x 3,239,121 3/1966 Kopf et a1.- ..227/l0 3,249,279 5/1966 Behrend et al. ..227/l0 2,957,176 10/1960 Henning et a1. ..227/8 FOREIGN PATENTS OR APPLICATIONS 208,313 3/ 1960 Austria ..227/ 10 51 Sept. 12, 1972 Primary ExaminerGranville Y. Custer, Jr. Attorney-Donald R. Motsko, H. Samuel Kieser and William W. Jones [5 7] ABSTRACT A power-actuated fastening tool of the type for driving fasteners by a propellant charge wherein a fastener driving member has an enlarged head portion. The head portion is so designed that a portion of the gases generated by the propellant charge may bleed from the rearward side to the forward side thereof to reduce recoil and buffer the fastener driving member. In addition, a specially designed piston member is provided for driving threaded fasteners wherein the piston has a bore extending into its forward end with the innermost portion of the bore being defined by a conical wall. The tool is so designed that power adjustment is obtained by positioning the piston member into its driving position by insertion of a fastener into the muzzle end of the tool. The barrel guide slot and pawl member are so designed that upon opening of the tool, there will be planar contact between the two members.

11 Claims, 8 Drawing Figures PATENTEDSEP I 2 I972 3 590 535 SHEET 1 OF 2 ATTORNEY PATENTEDSEP 12 m2 sum 2 or 2 INVENT OR 1 ANDREW G. BAKOLED/S POWDER-ACTUATED TOOL This invention relates generally to powder-actuated tools for driving fasteners or the like into masonry, concrete, wood, steel or the like. More particularly, this invention relates to such tools of the type which utilize a piston.

One object of the present invention is'to provide a piston-type powder-actuated fastening tool having an improved system for buffering the system.

A further object of the present invention is to provide a powder-actuated piston-type fastening tool wherein recoil is reduced.

A still further object of the present invention is to provide an improved method of obtaining power adjustment in a piston-type tool which canaccommodate fasteners of various lengths.

Yet another object'of the present invention is to provide an improved piston for use in a'powder-actuated tool which is especially adapted for driving threaded fasteners from a zero standoff position.

Yet still another object of the present invention is to provide an improved arrangement to guide the barrel relative to the housing in a powder-actuated tool.

These and other objects and advantages will become more apparent by reference to the following description of a preferred embodiment and to the accompanying drawings in which:

FIG. 1 is a transverse sectional view of a powder-actuated tool constructed in accordance with the present invention;

FIG. 2 is a cross sectional view taken along the lines 22 of FIG. 1;

FIG. 3 is a cross sectional view taken along the lines 3-3 of FIG. 1; t

FIG. 4 is a partial view of the outside surface of the barrel taken along the lines 4'4 of FIG. 3;

FIG. 5 is a cross sectional view taken along the lines 5-5 of FIG. 1;

FIG. 6 is a partial sectional view taken along the lines 66 of FIG. 1; I

FIG. 7 is an enlarged sectional view of the muzzle end of the tool showing details of the piston member; and

FIG. 8 is a transverse sectional view similar to the view of FIG. 1, but showing the components of the tool in their position after the tool has been fired.

Referring more specifically to the drawings, FIG. 1 shows a tool constructed in accordance with the present invention having a housing 2 including a tubular forward portion 4 and a rearward portion 6. The tubular forward portion 4 includes an elongated opening 8 to provide access for loading a propellant charge. The rearward portion 6 of the housing 2 houses the firing mechanism 10 and also includes a pistol grip 12 and a trigger guard 14.

The firing mechanism 10 includes a breech block 16 having a frusto-conical opening 18 therein. firing pin 20 is mounted behind the breech block 16 for axial movement in the housing 2 and includes a frusto-conical nose portion 22, a body portion 24 and a rearwardly extending rod portion 26. The firing pin 20 is urged forwardly by a suitable spring member 28. A detent member 30 extends radially downwardly from the body portion 24 of the firing pin 20. The detent member 30 is spring biased outwardly by suitable spring means 32.

A cocking rod 34 is mounted for reciprocation in the rearward portion 6 of the housing 2 and includes a forward portion 36 extending through the breech block 16 and into the tubular forward portion 4 of the housing 2. The cocking rod 34 may be spring biased forwardly by a suitable spring member 38. The cocking rod may also include an elongated opening 40 through which the detent member 30 on the firing pin 20 may extend.

A trigger member 42 having a sear portion 44 may be pivotally mounted above the trigger guard 14 by a pivot pin 46. The trigger is resiliently urged away from the firing position by spring member 48.

A barrel assembly 50 is reciprocally mounted within the tubular portion 4 of the housing 2 and extends from the muzzle end thereof. The barrel assembly includes a barrel member 52 having a bore 54 therein. A cartridge receiving chamber 56 is provided at the breech end of the barrel member for the reception of a propellant charge 58. The barrel assembly 50 also includes a muzzle bushing 60 which has a bore 62 of lesser diameter than the bore in the barrel member 52 and is threadedly received within the forward end of the barrelmember 52. A sheath member 64 surrounds the muzzle end of the barrel member 52 and includes an intumed flange 66 which is positioned between the forward edge 68 of the barrelmember 52 and a shoulder 70 on the external surface of the muzzle bushing 60.

A piston member 72 may be mounted for reciprocal movement within the barrel assembly 50. The piston member 72 includes an enlarged, generally cylindrical head portion 74, the outer surface of which is in sliding relationship with'the bore 54 of the barrel member 52 and a reduced, elongated, cylindrical shank portion 76 extending forwardly from the head portion 74. The shank portion 76 includes a tapered portion 78, which tapers down to a portion 79 having a diameter equal to the internal diameter of the muzzle bushing 60. The tapered portion 78 is adapted to abut a taper 80 in the rearward end of the muzzle bushing 60 to stop the piston in the event of overdrive thereof.

The outer surface of the head portion 74 may contain a circumferentially extending groove 81 in which may be mounted a split piston ring 82. The outer surface of the head portion 74 is also provided with an axially extending groove 84. The piston ring 82 has a portion 85 turned into the head portion 74 so that the piston ring 82 is positioned so that the split thereof is intercepted by the groove 84 whereby communication is provided between the chamber behind the rearward face 86 of the piston upon which the gases act and the chamber in front of the forward face 88 of the head portion 74.

A sleeve member 90 is mounted within the barrel member 52 and has a forward, outwardly extending flange 92 positioned between the rearward end of the muzzle bushing 60 and a shoulder 94 in the barrel member 52 to hold the sleeve member 90 in place in the tool. A rubber O-ring 93 is squeezed between the flange 92 and shoulder 94 which acts as a gas seal and keeps the threads between the muzzle bushing 60 and barrel member 52 clean as well as causing the threads to friction lock to prevent the muzzle bushing from loosening due to vibration. The sleeve member 90 has a plurality of gas escape ports 95 which are aligned with gas escape ports 97 in the barrel member 52. The

sheath member 64 has a portion of its rearward edge cut away as indicated at 99 to provide a gas escape path. The rearward end of the sleeve 90 has an intumed flange 96 with which the shank portion 76 of the piston member 72 has sliding engagement. Both the internal surface of the flange 96 and the external surface of the sleeve adjacent the rearward end thereof have circumferentially extending grooves 98 therein which act as gas seals.

The outside surface of the barrel member is provided with an axially extending groove 100 which has straight parallel side walls. The rearward end of the groove 100 is intersected by a transversely extending groove 102 which also has straight parallel side walls.

A pawl member 104 is mounted in a housing 106 attached to the tool housing 2 and is spring biased into the groove 100 by means of a spring 108. As will be seen particularly in FIG. 6, the sides of the portion 109 of the pawl member 104 which extend into the groove 100 are planaras indicated by 110 and 112. Also the rearward side of portion 109 of the pawl member 104 is also planar so that when the barrel member is moved forward relative to the housing, the flat side 1 14 of the pawl member 104 will contact the flat wall of groove 1 02 thereby providing area contact between the two members. The width of groove 102 is less than the front to rear dimension of portion 109 of the pawl member 104 to prevent relative rotation of the barrel with respect to the housing when the barrel is in its forward position relative thereto.

' Referring to FIG. 7, the muzzle bushing 60 has an axially extending slot 116 extending to the internal surface in the forward end thereof. A wire spring member 118 has a portion 120 wrapped around the external surface of the muzzle bushing 60 and a bowed'end portion 122 extending into the groove with the how 124 thereof projecting into the interior thereof. The spring 118 serves to resiliently hold the washer member 126 which is mounted on the shank portion 128 of a fastener'l30 in place in the muzzle end of the tool.

FIG. 7 shows the details of the forward or ram end of the piston member 72 which is especiallyconstructed to drive .fasteners such as fastener 130 having a threaded head portion 131 thereon. The piston member 72 has a counterbore 132 extending into its forward end. The counterbore has an inwardly tapering first portion 134 which tapers from a diameter larger than the external thread diameter to a diameter about equal to the external thread diameter. A cylindrical intermediate portion 136 having a diameter equal to or just slightly greater than the external thread diameter of the fastener connects the first portion 134 with a conical inner portion 140.

At the beginning of the operating sequence, the piston member 72 is normally in its forward position as shown in- FIG. 8. At this point a fastener, such as fastener 130, may be inserted into the muzzle bushing 60 of the too] until the washer 126 thereon is engaged by the bowed portion 122 of the spring 120 which serves to hold the fastener in place. The insertion of the fastener 130 into the tool serves to return the piston member 72 to its firing position and also serves to provide ameans for power adjustment. The volume of the chamber between the end face 86 of the head portion 74 of the piston member 72 and the cartridge receiving chamber 56 determines the power. level for a given fastening operation. The larger the initial volume of this chamber, the less power is available for a given fastening operation. The longer a given fastener, the further to the rear it will push the piston member 72 when it is inserted into the muzzle bushing 60. Thus with a larger fastener, the initial volume in the chamber behind the end face 86 will be less, thereby providing more power than would be available if a shorter fastener was used. On the other hand, with a shorter fastener, which does not need as much power, the chamber will be larger.

In addition, it is to be noted that grooves and 102 in the barrel do not extend into the bore 54 thereof. Thus the chamber-behind the head portion 74 of the piston, as well as the chamber in front of the head portion 74 is imperforate. This has the advantage of v providing a tool which is less noisy than tools wherein such chambers are perforated as by aslot for the reception of a pawl for piston return and barrel guidingfunctions.

After a fastener is inserted, the tool may be moved to its breech open position to expose thecartridge receiving chamber 56 for the insertion of a new cartridge. This is accomplished by pulling the barrel assembly 50 forward relative to the housing 2 until the portion 109 of the pawl member 104 abuts the end of the groove 100. By virtue of the transverse groove 102 intersecting the end of groove 100, a straight wall portion is provided against which the planar face 114 of the pawl member 104 will abut. This provides area contact on both surfaces. This feature reduces burring and peening which might result if one or both of the surfaces were round and presented only line contact.

To fire the tool, the operator must push down on the housing 2 to move the housing 2 forward relative to the barrel assembly 50. In so doing, the cocking rod 34 abuts the rearward end of the barrel member 52 so that the housing 2 moves forward relative thereto. By virtue of the detent member 30 extending into the opening 40 in the cocking rod 34, the housing 2 also moves forwardly with respect to the firing pin 20 until the forward face of the breech block 16 abuts the rearward surface of the barrel assembly 50. At this point, the detent member 30 is in operable alignment with the sear portion 44 of the trigger member 42, so that by pulling the trigger member 42, the sear portion 44 will release the detent member 30 from the opening 40 in the cocking rod 34 and the firing pin 20 will fly forward under the action of its spring member 28 until the nose portion 22 thereof projects through the frusto-conical opening 18 in the breech block 16 and actuates the cartridge 58.

The gases generated by the ignition of the cartridge 58 act upon the rearward face 86 of the piston member 72 to drive the piston member forwardly and in turn drive the fastener into the work surface. As the piston member 72 moves forward, some of the gases behind the rearward face 86 are bled through groove 84 into the chamber between the forward face88 of the head portion 74 of the piston member 72 and the rearward face of the flange 96 on sleeve member 90. When the piston member approaches its driven position as shown in FIG. 8, the chamber in front of the head portion of the piston is smaller than the chamber behind the rearward face 86. The gases trapped in the forward chamber serve to buffer the piston at the end of its stroke. Moreover, as the piston member is moving forward, and as the gases are acting on the sleeve member 90 which forms a part of the barrel assembly of the tool, the bled gases serve to hold the muzzle bushing of the tool against the work surface. This feature, coupled with the fact that the forward force of the gas upon the flange 96 of sleeve member 90 in the barrel member tends to negate the rearward force of the gas acting upon the cartridge chamber, reduces recoil of the tool. In addition, at the end of the firing stroke, if the barrel assembly tends to move away from the work surface relative to the piston member 72, the tapered portion 80 in the muzzle bushing 60 will abut the tapered portion 78 of the piston member 72. As the gas acting upon the cartridge chamber which tends to move the barrel assembly away from the work surface also acts upon the piston member forcing the piston member in the opposite direction, when the muzzle bushing abuts the piston member, the rearward force on the barrel assembly will be canceled out.

As will be noted, this tool is designed to fire a fastener from a zero standoff position. That is, from a position wherein the tip of the fastener is substantially flush with the front surface of the muzzle bushing which means that when the tool is applied to a work surface, the fastener tip will be positioned against the work surface. The design of the front end of the piston member 72 with the counterbore therein, permits the tool to be used to fasten fasteners having a threaded head portion. The tapered portion 134 of the counterbore serves as a guide to insert the threaded head portion into the counterbore, while the cylindrical portion serves to-support the fastener. Due to the conical shape of the end of the counterbore, a compressive force is applied to the fastener causing the end thereof to be extruded into the conical portion of the counterbore. Not only does this prevent damaging of the threads of the fastener, but also, the conical shape which is formed on the end of the threaded fastener acts as a lead-in chamfer permitting a threaded nut to be screwed onto the fastener easily.

What is claimed is:

1. In a power-actuated fastening tool of the type for driving fasteners by a propellant charge:

a. a housing;

b. means defining a barrel mounted in said housing;

0. a fastener driving member mounted in said barrel for movement between a driving position and a driven position, said fastener driving member including an enlarged head portion and a reduced elongated ram portion extending forwardly from said head portion;

(1. means for directing the gas generated by the ignition of a propellant charge to the rearward face of the enlarged head portion;

. means in said head portion for permitting a portion of the gas on the rearward side of said head portion to bleed to the forward side thereof; and I f. means in said barrel forming a gas chamber in conjunction with the forward face of the head portion which diminishes in volume as said piston member moves from its driving position to its driven position.

2. In the power-actuatedfastening tool of claim 1, said barrel having a cartridge receiving chamber com municating with the interior of said barrel at a point rearward of the head portion of the fastener driving member when said fastener driving member is in the driving position and sleeve means in said barrel having a flange thereon in gas-sealing relationship with the reduced elongated ram portion of said fastener receiving member, said flange defining a portion of said gas chamber.

3. In the power-actuated fastening tool of claim 2, said head portion of said fastener driving member having an axial groove therein extending from its rearward face to its forward face.

4. In the power-actuated tool of claim 3, said head portion of said fastener driving member having a circumferential groove, a split piston ring mounted within said groove, one end of said piston ring being turned into a bore in said head portion, said axial groove intersecting said circumferential groove and said one end of said piston ring being spaced from the other end across the width of said axial groove. I

5. In the power-actuated tool of claim 1,.said means defining a barrel including a barrel member and a muzzle bushing threadedly attached to said barrel member, said means in said barrel including a sleeve member having an. outwardly extending flange at one end secured between said muzzle bushing and said barrel member and an inturned flange at the other end in engagement with the ram portion of said fastener driving member.

6. A power-actuated tool of the type utilizing a propellant charge for driving fasteners, said tool including a housing, a barrel assembly mounted in said housing, a fastener driving member mounted in said housing for movement between a driving position and a driven position, said fastener driving member including an enlarged head portion and a reduced elongated ram portion, a cartridge receiving chamber in said barrel assembly'communicating with the rearward face of said enlarged head portion, a slot in said enlarged head portion for permitting gases fromv the ignition of a propellant charge to pass from the rearward side of said head portion to the forward side thereof, a tapered portion on said rarn portion, a tapered portion in said barrel assembly, said tapered portion of said ram portion adapted to abut the tapered portion in said barrel assembly if rearward movement of said barrel assembly relative to said fastener driving means occurs at the end of the fastening operation.

7. A power-actuated tool of the type utilizing a propellant charge, said tool comprising a housing, a barrel member mounted in said housing for movement between a breech closed position and a breech open position, a piston mounted in said barrel for movement between a driving position and a driven position, said piston including an enlarged head portion and a reduced elongated ram portion, said barrel member having a powder propellant charge receiving chamber at its breech end, said piston being positioned a predetermined distance from the cartridge receiving chamber when it is in said driving position and being moveable into said position from said driven position by the insertion of a fastener into the muzzle end of the barrel to engage the forward end of the piston to move the piston rearwardly in thetool until the fastener is in a position to be driven.

8. In the power-actuated tool of claim 7 said barrel member having a groove in its longitudinal wall, said groove extending only a portion of the way into the wall, and a pawl member attached to said housing and extending into said groove to guide said barrel member during its movement relative to said housing.

9. The power-actuated tool of claim 8 wherein the tip of a fastener is substantially flush with the muzzle end of the barrel member when said fastener is in a position to be driven.

10. In a power-actuated tool, a housing having a tubular forward portion, a barrel mounted in said forward portion for movement between a breech open and a breech closed position, said barrel having an axially extending groove in its outer surface, a pawl member mounted in said housing and extending into said groove, a second groove having spaced parallel side walls in the outer surface of said barrel extending perpendicular to said first groove having its rearward end terminating at said second groove whereby said second groove presents a planar end face for said first groove, that portion of said pawl member facing said second groove having a planar face.

11. A power-actuated tool according to claim 10 wherein the thickness of the pawl member in a direction parallel to the width of said first groove is greater than the width of said second groove.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIGN Patent No. 3,690 ,536 te September 12 1972 Inventor(s) Andrew G. Bakoledis It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, line 66, please delete "piston" and insert --fastener driving- Signed and sealed this 10th day of April 1973.

(SEAL) Attest:

' EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents r 7 P C-.050 (10-69) USCOMM-DC 60376-1 69 u.s. GOVERNMENT PRINTING OFFICE: 1969 o-ass-aaa 

1. In a power-actuated fastening tool of the type for driving fasteners by a propellant charge: a. a housing; b. means defining a barrel mounted in said housing; c. a fastener driving member mounted in said barrel for movement between a driving position and a driven position, said fastener driving member including an enlarged head portion and a reduced elongated ram portion extending forwardly from said head portion; d. means for directing the gas generated by the ignition of a propellant charge to the rearward face of the enlarged head portion; e. means in said head portion for permitting a portion of the gas on the rearward side of said head portion to bleed to the forward side thereof; and f. means in said barrel forming a gas chamber in conjunction with the forward face of the head portion which diminishes in volume as said piston member moves from its driving position to its driven position.
 2. In the power-actuated fastening tool of claim 1, said barrel having a cartridge receiving chamber communicating with the interior of said barrel at a point rearward of the head portion of the fastener driving member when said fastener driving member is in the driving position and sleeve means in said barrel having a flange thereon in gas-sealing relationship with the reduced elongated ram portion of said fastener receiving member, said flange defining a portion of said gas chamber.
 3. In the power-actuated fastening tool of claim 2, said head portion of said fastener driving member having an axial groove therein extending from its rearward face to its forward face.
 4. In the power-actuated tool of claim 3, said head portion of said fastener driving member having a circumferential groove, a split piston ring mounted within said groove, one end of said piston ring being turned into a bore in said head portion, said axial groove intersecting said circumferential groove and said one end of said piston ring being spaced from the other end across the width of said axial groove.
 5. In the power-actuated tool of claim 1, said means defining a barrel including a barrel member and a muzzle bushing threadedly attached to said barrel member, said means in said barrel including a sleeve member having an outwardly extending flange at one end secured between said muzzle bushing and said barrel member and an inturned flange at the other end in engagement with the ram portion of said fastener driving member.
 6. A power-actuated tool of the type utilizing a propellant charge for driving fasteners, said tool including a housing, a barrel assembly mounted in said housing, a fastener driving member mounted in said housing for movement between a driving position and a driven position, said fastener driving member including an enlarged head portion and a reduced elongated ram portion, a cartridge receiving chamber in said barrel assembly communicating with the rearward face of said enlarged head portion, a slot in said enlarged head portion for permitting gases from the ignition of a propellant charge to pass from the reArward side of said head portion to the forward side thereof, a tapered portion on said ram portion, a tapered portion in said barrel assembly, said tapered portion of said ram portion adapted to abut the tapered portion in said barrel assembly if rearward movement of said barrel assembly relative to said fastener driving means occurs at the end of the fastening operation.
 7. A power-actuated tool of the type utilizing a propellant charge, said tool comprising a housing, a barrel member mounted in said housing for movement between a breech closed position and a breech open position, a piston mounted in said barrel for movement between a driving position and a driven position, said piston including an enlarged head portion and a reduced elongated ram portion, said barrel member having a powder propellant charge receiving chamber at its breech end, said piston being positioned a predetermined distance from the cartridge receiving chamber when it is in said driving position and being moveable into said position from said driven position by the insertion of a fastener into the muzzle end of the barrel to engage the forward end of the piston to move the piston rearwardly in the tool until the fastener is in a position to be driven.
 8. In the power-actuated tool of claim 7 said barrel member having a groove in its longitudinal wall, said groove extending only a portion of the way into the wall, and a pawl member attached to said housing and extending into said groove to guide said barrel member during its movement relative to said housing.
 9. The power-actuated tool of claim 8 wherein the tip of a fastener is substantially flush with the muzzle end of the barrel member when said fastener is in a position to be driven.
 10. In a power-actuated tool, a housing having a tubular forward portion, a barrel mounted in said forward portion for movement between a breech open and a breech closed position, said barrel having an axially extending groove in its outer surface, a pawl member mounted in said housing and extending into said groove, a second groove having spaced parallel side walls in the outer surface of said barrel extending perpendicular to said first groove having its rearward end terminating at said second groove whereby said second groove presents a planar end face for said first groove, that portion of said pawl member facing said second groove having a planar face.
 11. A power-actuated tool according to claim 10 wherein the thickness of the pawl member in a direction parallel to the width of said first groove is greater than the width of said second groove. 